Javafx Combox和ListView

Question

我是javafx的新手。我想使用Combox更改ListView的选择模型

有我的代码：

private String[] selectionMode = {"SINGLE","MULTIPLE"};
​private ComboBox<String> cboSelectionMode = new ComboBox<>();
​private String[] items = {"America","British","China","Denmark","Germany",
​​​"Japan","Korea"};
​
​@Override
​public void start(Stage primaryStage) {
​
BorderPane paneForSelection = new BorderPane();
paneForSelection.setLeft(new Label("Choose Selection Mode: "));
    ​​ paneForSelection.setCenter(cboSelectionMode);
cboSelectionMode.setPrefWidth(125);
cboSelectionMode.setValue("SINGLE");
​​
​​ListView<String> lvItems = new ListView<>(FXCollections.observableArrayList(items));

​​FlowPane paneForText = new FlowPane();
​​
​​ObservableList<String> selection = FXCollections.observableArrayList(selectionMode);
​​cboSelectionMode.getItems().addAll(selection);
​​cboSelectionMode.setOnAction(e ->{
​​​paneForText.getChildren().clear();
​​​if(cboSelectionMode.getValue()=="SINGLE") {
​​​​lvItems.getSelectionModel().setSelectionMode(SelectionMode.SINGLE);
​​​}
​​​else if(cboSelectionMode.getValue()=="MULTIPLE") {
​​​​lvItems.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
​​​}
​​});​
​​
​​lvItems.getSelectionModel().selectedItemProperty().addListener(ov ->{
​​​paneForText.getChildren().clear();
​​​paneForText.getChildren().add(new Label("Selected items are "));
​​​for(Integer i: lvItems.getSelectionModel().getSelectedIndices()){
​​​​Label lb = new Label(items[i]+" ");
​​​​paneForText.getChildren().add(lb);
​​​}
​​}); 

但我发现了两个问题：

1.当我将选择模型从“SINGLE”更改为“MULTIPLE”时，我的窗格上有一个灰色区域。 我不能删除它，除非我点击它。但如果我点击它，它将被选中。如果我不删除它但只选择其他项目，它也将被选中。除了点击它之外我怎么能删除它？

2.在“MULTIPLE”模型中，它有时会出现错误“ArrayIndexOutOfBoundsException”。我不知道为什么以及如何解决它。